South Korea says an alleged hacking attack that originated in China compromised the personal information of millions of the cyber-savvy country's internet users.

The Korea Communications Commission said in a statement Thursday that hackers purportedly attacked popular internet and social media sites Nate and Cyworld and that information of 35 million people was stolen.

The regulator said the attack took place Tuesday and that operator of the sites, SK Comms, alleged the source was from internet protocol addresses in China.

IP addresses are the web equivalent of a street address or phone number.

South Korea has been subject to such attacks with blame frequently pinned on hackers using addresses in China. China has denied all charges of hacking in the past.